Chapter 21 (Genetic Inheritance)

Question 1

Describe genotype and phenotype.

Answer 1

An organism’s genotype is the set of genes that it carries. An organism’s phenotype is all of its observable characteristics, which are influenced both by its genotype and the environment. For example, differences in the genotypes can produce different phenotypes.

Question 2

Know the term for the location of a gene on the chromosome

Answer 2

The region of the chromosome at which a particular gene is located is called its locus. Each locus contains one allele of a gene.

Question 3

What is an allele?

Answer 3

One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Question 4

What is the difference between dominant and recessive alleles?

Answer 4

Copies of genes that are always expressed, or used to make traits, over other alleles are called dominant, while the copies of genes that aren’t expressed if a dominant allele is around are called recessive.

Question 5

Describe the difference between a homozygous and heterozygous genotype

Answer 5

Homozygous means that both copies of a gene or locus match while heterozygous means that the copies do not match. Two dominant alleles (AA) or two recessive alleles (aa) are homozygous. One dominant allele and one recessive allele (Aa) is heterozygous.

Question 6

Describe the importance of gamete formation in trait inheritance

Answer 6

• Gametes are male and female. Gamete half genetic information. Some genes come from the female and some from the male which creates genetic variation.
• If the gamete formation was the exact same, all brothers would look the same and all sisters would look the same.

Question 7

Definition and purpose of a Punnett square:

Answer 7

The Punnett square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment.

Question 8

Define the term polygenic trait

Answer 8

A polygenic trait is one whose phenotype is influenced by more than one gene.

Question 9

Define the term multifactorial trait

Answer 9

Multifactorial inheritance means that many factors are involved in causing a health problem. The factors are usually both genetic and environmental.

Question 10

Differentiate between a polygenic trait and a multifactorial trait

Answer 10

• Polygenic traits: such as skin color and height are controlled by more than one set of alleles.
• Multifactorial traits: usually polygenic with an environmental influence.

Question 11

Describe incomplete dominance and codominance; know the definition of both terms

Answer 11

In incomplete dominance a heterozygous individual blends the two traits. With codominance you’ll see both alleles showing their effects but not blending

Question 12

Differentiate between autosomes and sex chromosomes

Answer 12

Autosomes are chromosomes that don’t carry any genes that determine t0he sex of the individual. Sex chromosomes carry sex-determining genes.

Question 13

Describe which type of trait would be sex-linked

Answer 13

So for the genes on the sex chromosomes, males have just one copy. The Y chromosome has very few genes, but the X chromosome has more than 1,000. Well-known examples in people include genes that control color blindness and male pattern baldness. These are sex-linked traits